Spring connection for vibratory conveyor

ABSTRACT

A spring connection for a vibratory conveyor having a trough member including a side wall, includes two fasteners which are welded to the side wall. The connection includes a spring connection plate with corresponding fastener holes to receive the fasteners. Nuts are threaded onto the fasteners and torqued down to clamp the connection plate onto the side wall of the trough member. The spring connection plate carries a spring bracket with a mounting hole for connection to one or more springs.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to vibratory conveyors. Particularly, theinvention relates to a system for attaching base mounted springs of avibratory conveyor to a trough member.

BACKGROUND OF THE INVENTION

Vibratory conveyors are used in many industrial material handlingprocesses to convey bulk process material from one point in the processflow to another. For example, in the snack food industry, vibratoryconveyors are used to convey and distribute potato chips, popcorn, cornchips and the like, from the cooking processes to the packagingmachines. Such vibratory conveyors are generally of the resonant, twomass design to minimize operating power, and to isolate the generateddynamic operating forces from the support structure of the conveyor andother surrounding equipment.

A resonant, two mass design vibratory conveyor includes a base memberthat is supported by isolating spring members from a support structure.The spring members adapt the conveyor to the elevation required for theconveyor to be integrated into the material flow path. The base memberin turn is connected to a conveying trough member by leaf springsextending between the base and trough members. The longitudinal axis ofeach of the springs is at a preferred angle to the vertical, imparting adirected force to the material during operation and causing the materialto flow along the trough member.

The conveyor also includes a drive mechanism connected between the baseand trough members. The drive mechanism acts to cause the base andtrough members to vibrate or move back and forth relative to oneanother. The drive mechanism may be a motor and crank arm system; or anelectromagnetic system with the electromagnet core connected to the basemember and the electromagnet armature connected to the trough member; ora motor driven rotating eccentric weight exciter mounted to either thebase member or the trough member, usually the base member; or some othersimilar drive system. The natural frequency of the conveyor's mass andspring system is set close to the operating speed of the conveyor totake advantage of the phenomenon of resonance, wherein energy stored inthe spring system as it operates is returned to be in phase with theapplied driving force. This setting reduces the power required tooperate the conveyor to about 25% of what would be required in a directdrive system.

A typical practical conveyor uses several groups or stacks of leafsprings mounted between the base member and the trough member. Thegroups are spaced-apart along the length of the conveyor. Since theoperating forces are applied through these spring groups, large dynamicreversing stresses occur at the spring group attachment points, andtherefore the design for the attachment points must be very robust. Tobe practical from an overall weight, cost, and sanitary designperspective, the trough member is usually constructed of relatively thinstainless steel sheet stock. If the spring groups were mounted directlyto the trough member, the side walls would be subjected to excessivevibratory stresses and would soon fail and tear out. Therefore, thespring groups are usually connected to a robust spring mounting bracketstrongly welded to a mounting plate that is designed to spread theforces out to acceptably low stress levels along the trough member sidewall, to prevent failure. The mounting plate is then typically welded orbolted to the trough member side wall.

Bolting the spring mounting plate to the trough member side wall is alow cost connection, making the design attractive competitively, but ithas several drawbacks making it less desirable in operation. The headsof the bolts protrude into the flow of the material in the trough. Thismay create a sanitary problem. Fine particles can lodge in the crevicesaround the bolt head and provides a place for bacteria to grow, makingit difficult to assure that cleanliness standards are maintained at alltimes. The heads of the bolts may disrupt smooth material flow in thetrough and adversely affect material flow rate. Also, the bolts must bemaintained tight to provide the required clamping force to preventrotating of the bolt head and scoring of the trough interior wall, oreven worse, the failure of the connection.

Some manufacturers, such as FMC Corporation's Material HandlingEquipment operation, have used a combination cast spring bracket andmounting plate that is inert gas welded to the trough wall. The weldextends around the perimeter of the mounting plate for a secure, lowstress, sanitary connection. This method addresses and eliminates thedrawbacks of the bolted-on connection, but the design is less attractivecompetitively. The inert gas welding provides a neat, clean weld finish,but some post weld clean-up is still required, particularly on theinterior of the trough wall where the weld heating can discolor thestainless steel side wall material. The trough wall must be buffed andpolished to return it to its original condition. Also, the welding heatcan cause distortion in the trough member side wall if not carefullyapplied, requiring straightening of the trough member and furtherpolishing.

The present inventors have recognized that it would be desirable toprovide a cost competitive spring connection while maintaining thesanitary and material flow characteristics of the welded mounting platetype spring connection.

SUMMARY OF THE INVENTION

The invention is directed to a vibratory conveyor and an apparatus andmethod to provide an effective and cost advantageous spring connectionfor connecting springs to a conveyor trough member, particularly,connecting springs to a relatively thin side wall of the trough member.The spring connection for the vibratory conveyor includes one or morefasteners that is (are) welded to the side wall. The connection includesa spring connection plate with a corresponding fastener hole to receiveeach fastener. A nut is threaded onto each fastener and torqued down toclamp the connection plate onto the side wall of the trough member. Thespring connection plate carries a spring bracket with a mounting holefor connection to one or more springs.

According to the preferred arrangement, the vibratory conveyor includesa base member, a trough member having a side wall, and a plurality ofsprings, such as leaf springs, extending from the base member to thetrough member to support the trough member from the base member. Atleast one fastener is provided having a head and a threaded shank. Theshank penetrates through the side wall, and the head is fixed to theside wall. A connection plate is connected to at least one of thesprings, and the shank penetrates the fastener hole of the connectionplate. A nut is threaded onto each shank and tightened to fasten theconnection plate to the side wall.

Preferably, the head of each fastener is welded all around to an insidesurface of the side wall with the shank penetrating the side wall andextending outside the side wall. Also, the head can have a beveledprofile to minimize flow disruption inside the trough. The head can bewelded by an inert gas welding technique such as by TIG welding.

Other features and advantages of the present invention shown will becomereadily apparent from the following detailed description, theaccompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of a vibratory conveyor that incorporatesspring connections of the present invention;

FIG. 2 is an enlarged, fragmentary elevational view of a springconnection taken from FIG. 1, with springs removed for clarity;

FIG. 3 is a rear view of the spring connection shown in FIG. 2, takengenerally along line 3--3 of FIG. 4;

FIG. 4 is an enlarged, fragmentary sectional view taken generally alongline 4--4 of FIG. 1, with springs removed for clarity; and

FIG. 5 is an elevational view of a weld stud taken from FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

While the present invention is susceptible of embodiment in variousforms, there is shown in the drawings and will hereinafter be describeda presently preferred embodiment with the understanding that the presentdisclosure is to be considered an exemplification of the invention andis not intended to limit the invention to the specific embodimentillustrated.

FIG. 1, illustrates a vibratory conveyor 8 including a conveying troughmember 11 mounted by spring groups or stacks 9 onto a base member 10.The spring groups 9 are each connected to the trough member 11 by a castspring bracket 14 that is carried on an integral connection plate ormounting plate 12. The mounting plate is bolted to a side wall 11a ofthe trough member 11 by stud members 18, 18. The mounting plates arespaced at intervals along the length of the conveying trough member 11.Each cast spring bracket 14 is angled at a specific drive angle 26 fromthe vertical.

The base member 10, comprises two rectangular steel tubes or rectangularplates spaced apart and connected by steel cross members (notillustrated). Base spring mounting blocks 21 are rigidly welded orotherwise connected to the base member 10 at spaced intervals along thelength of the base member 10, and angularly align with the cast springbrackets 14. The base spring mounting blocks 21 are also arranged at thespecific drive angle 26 from the vertical.

Each spring group 9 includes one or more leaf spring members 22 whichare bolted at one end to the cast spring bracket 14 on the trough member11, and at the opposite end to the base spring mounting block 21. Aspring bolt hole 16 formed through the bracket 14 is used to attach thespring members 22. The plurality of spaced-apart groups or stacks 9 ofspring members support the trough member 11 above the base member 10.

A drive member 23 is mounted, with the aid of brackets and bolts (notillustrated), to the base member 10 at the specific drive angle 26 fromthe horizontal, to provide a force perpendicular to the leaf spring'smounting angle 26, when operating. Coil spring isolation members 24connect the base member to the support structure 25, and absorb the bulkof the dynamic forces generated by the operating conveyor from beingtransmitted to the support structure 25.

Referring to FIG. 2, the cast spring mounting bracket 14 and themounting plate 12 can be seen in their bolted position on the side wall11a of the trough member 11. The plate 12 is connected to the side wall11a by the stud members 18, 18, lock washers 17, 17, and acorn nuts 13,13. Also noted in this view is the spring bolt hole 16 in the springmounting bracket 14 and the substantial cast fillet 15 surrounding thebase of the spring mounting bracket 14.

FIG. 3 shows the heads 18a, 18a of the stud members 18, 18 and acontinuous inert gas weld bead 19, 19 around each of the entirecircumferences of the heads of the stud members 18, 18.

FIG. 4 illustrates the cast spring mounting bracket 14 and integralmounting plate 12 bolted on the side wall 11a of the trough member 11,by the stud member 18, the lock washer 17 and acorn nut 13. Also shownis the continuous inert gas weld bead 19, the spring bolt hole 16, themounting plate 12, locating holes 28 in the side wall of the troughmember 11, and the substantial cast fillet 15 surrounding the base ofthe spring mounting bracket 14.

As shown in FIG. 3 and in FIG. 4, the continuous inert gas weld bead 19extending around the entire circumference of the head of each of thestud members 18, 18 provides a substantial length of weld to distributethe stress loads generated by the leaf spring members 22 and exertedthrough the cast spring bracket 14 and the integral mounting plate 12.The weld bead 19 completely seals the joint between the edge of the headof the bolt and the inside surface of the trough side wall 11a to make asanitary connection free of voids and cracks that might support thegrowth of harmful bacteria.

The method of the invention therefore includes locating and cutting outthe two mounting plate locating holes 28 in the side wall 11a of thetrough member 11. The stud members 18, 18 are inserted into the locatingholes 28 from the interior side of the trough member 11, such that theheads of the stud members 18, 18 are flush against the interior of theside wall 11a of the trough member 11, protruding into the path of thematerial flow. The next step is to use an inert gas welding technique,such as TIG welding, to produce a continuous weld bead around the entirecircumference of the heads 18a, 18a of the stud members 18, 18. Themounting plate 12 is then placed over the protruding threaded shanks18b, 18b of the stud member 18, 18 on the exterior side of the troughmember 11, and lock washers 17, 17 are placed on the shanks. Acorn nuts13, 13 are threaded onto the shanks and torqued into place, securelyclamping the mounting plate 12 to the exterior of the trough member 11.By using this method of assembly, reversing stresses generated by thevibratory conveyor are spread out to acceptably low levels along thetrough side wall.

FIG. 5 is a sketch of the custom made stud member 18, showing the head18a to have an angle of taper 29. The relatively large low profile headhas the angle of taper 29 from near the center of the stud to its edgeto minimize the disruption of the material bed as it flows past the head18a. In contrast, the heads of regular bolts protruding into thematerial flow can produce turbulence around the bolt head slowing thematerial flow.

From the foregoing, it will observed that numerous modifications andvariations can be effected without departing from the spirit and scopeof the novel concept of the present invention. It is to be understoodthat no limitation with respect to the specific embodiments disclosedherein is intended or should be inferred. The disclosure is intended tocover by the appended claims all such modifications as fall within thescope of the claims.

The invention claimed is:
 1. A vibratory conveyor, comprising:a basemember; a trough member having a side wall; a plurality of springsextending from said base member to said trough member to support saidtrough member from said base member; a connector plate connected to oneof said springs and having at least one fastener hole; and at least onefastener having a head and a threaded shank, said shank penetratingthrough said side wall, said head located within said trough member andsealed to said side wall, and said shank penetrating said fastener holeof said connector plate; and at least one nut, said nut threaded ontosaid shank to fasten said connector plate to said side wall.
 2. Theconveyor according to claim 1, wherein said head includes asubstantially beveled profile within said trough.
 3. The conveyoraccording to claim 1, further comprising a lock washer arranged betweensaid nut and said connector plate.
 4. The conveyor according to claim 2,wherein said head is beveled at an angle of taper around a circumferenceof said head.
 5. The conveyor according to claim 1, wherein said springscomprise leaf springs.
 6. A method of attaching a leaf spring to atrough member of a vibratory conveyor, comprising the steps of:providingat least one fastener having a head and a shank; attaching said fastenerto said trough member by fixing said head to said trough member;providing a connection plate having at least one fastener hole;inserting said shank through said fastener hole; and providing a nut andtightening said nut onto said shank to attach said connection plate tosaid trough member, wherein said step of providing said fastener isfurther defined in that said head has a beveled profile and is locatedagainst an inside surface of a side wall said trough member, and saidstep of fixing said head is further defined in that said head is weldedall around to said inside surface of said side wall.
 7. The methodaccording to claim 6, wherein said head is beveled at an angle of taperaround a circumference of said head.
 8. A method of attaching a leafspring to a trough member of a vibratory conveyor, comprising the stepsof:providing at least one fastener having a head and a shank; attachingsaid fastener to said trough member by fixing said head to said troughmember; providing a connection plate having at least one fastener hole;inserting said shank through said fastener hole; and providing a nut andtightening said nut onto said shank to attach said connection plate tosaid trough member, wherein said step of fixing said head is furtherdefined in that said head is welded to a side wall of said troughmember.
 9. The method according to claim 8, wherein said step of fixingsaid head is further defined in that said head is welded all around toan inside surface of a side wall of said trough member, and said shankpenetrates though said side wall.
 10. The method according to claim 8,wherein said step of fixing said head is further defined in that saidhead is welded to a side wall of said trough member by an inert gaswelding technique.
 11. The method according to claim 8, wherein saidstep of fixing said head is further defined in that said head is TIGwelded to a side wall of said trough member.
 12. A vibratory conveyor,comprising:a base member; a trough member having a side wall; aplurality of springs extending from said base member to said troughmember to support said trough member from said base member; a connectorplate connected to one of said springs and having at least one fastenerhole; and at least one fastener having a head and a threaded shank, saidshank penetrating through said side wall, said head fixed to said sidewall, and said shank penetrating said fastener hole of said connectorplate; and at least one nut, said nut threaded onto said shank to fastensaid connector plate to said side wall, wherein said head has aperimeter and is welded all around said perimeter to said side wall. 13.The conveyor according to claim 12, wherein said head is welded allaround said perimeter to an inside surface of said side wall.
 14. Amethod of attaching a leaf spring to a trough member of a vibratoryconveyor, comprising the steps of:providing at least one fastener havinga head and a shank; sealing said head to said trough member; providing aconnection plate having at least one fastener hole; inserting said shankthrough said fastener hole; and providing a nut and tightening said nutonto said shank to attach said connection plate to said trough member.